Neurolinguists from HSE University, together with radiologists from the National Medical and Surgical Center in Pirogov, have developed a Russian-language protocol for functional magnetic resonance imaging (fMRI) that maps individual language areas before neurosurgical operations. The study was published in Frontiers of Human Neuroscience.
When neurosurgeons operate on brain tumours, their objective is to remove the pathological tissue while preserving as much as possible the adjacent areas critical to the various motor and cognitive functions, including language. The ability to preserve language areas determines whether the patient will have language impairment after the operation and will be able to communicate easily with others, hold a job and lead an ordinary life.
The exact location of language areas differs from person to person, so special methods must be used to map them in each patient. The most accurate method is direct electrical stimulation during neurosurgery. But sometimes the neurosurgeon needs to know in advance where the language areas of a particular patient are to make the best possible plan for the operation. This preoperative mapping is carried out using a functional MRI, or fMRI. While in an MRI scanner, the patient performs language-related tasks. Data analysis shows which areas of the brain are activated.
Until now, most protocols for preoperative linguistic mapping by this method were developed in English. Scientists from HSE University have developed the first Russian-language fMRI protocol that uses a language task recommended by the international scientific community; sentence completion.
The patient should read aloud a sentence with the last word missing (such as “The audience watched a long time…”) and then end the sentence with an appropriate word (such as “play” or “movie”). This task is unique in that it involves both language production and sentence-level comprehension, which allows for comprehensive mapping of the patient’s language areas.
The researchers validated the protocol in a control group of 18 healthy Russian-speaking volunteers aged 30 to 53. This proved that the protocol successfully maps the most important language areas in the frontal and temporal lobes of the brain and reveals the individual lateralization of language function; that is, the extent to which this function relies on the left and right hemispheres of the brain. The researchers also demonstrated the high reliability of the protocol: each volunteer underwent the procedure twice with an interval of several weeks and the results were similar. This is the first protocol in the Russian language that has undergone such extensive validation.
The first stage of the study has been completed, showing the validity and reliability of the protocol in the control group. Now we do the most important part; testing the protocol in clinical practice, using it for preoperative voice mapping in patients with brain tumors and epilepsy. We plan to analyze whether the protocol works equally well in the clinical groups as in the control group. We will test to what extent its results match those of intraoperative mapping and, therefore, to what extent it should be applied in clinical practice.
Svetlana Malyutina, researcher at the HSE Center for Language and Brain and co-author of the article
National Research University Graduate School of Economics
Elin, K. et al. (2022) A new functional magnetic resonance imaging locator for preoperative language mapping using a sentence completion task: validity, choice of baseline, and test-retest reliability. Frontiers in human neuroscience. doi.org/10.3389/fnhum.2022.791577.